Solenoid operated trip mechanism



n 1958 w. F. HURLBURT, JR 2,839,929

SOLENOID OPERATED TRIP MECHANISM Filed Aug. '14, 1953 4 Sheets-Sheet 1INVENTOR W/LBUR E HURLBURT. JR.

ORNEY7 June 24, 1958 w. F. II-IURLBURT, JR 2,839,929

I SOLENOID OPERATED TRIP MECHANISM Filed Aug. 14. 1955 4 Sheets-Sheet s50 5 T1|: ."7.z 5;; 5a

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une 4, 1958 w. F. HURLBURT, JR 2,839,929

SOLENOID OPERATED TRIP'MECHANISM Filed Aug. 14. 1953 I 4 Sheets-Sheet 4INVENTOR: M451? A #024 30/??- Me.

United States Patent ()fiice SOLENOID OPERATED TRIP MECHANISM Wilbur F.Hurlburt, In, West Orange, N. J., assignor t Automatic Switch C0.,Orange, N. J., a corporation of New York Application August 14, 1953,Serial No. 374,283

Claims. (Cl. 74-2) My present invention relates generally to operatingmechanisms for valve stems or the like, and has particular reference tooperating mechanisms suitable for free-handle manual-reset valves.

In an installation of the character referred to, the setting of thevalve into and out of various positions is under the manual control ofan operator only so long as a certain condition, or a selected set ofconditions, is maintained; and in the event that any of the conditionsis or becomes different from What it should be, the valve automaticallycloses (or opens, as the case may be) and the manual control is renderedcompletely inefit'ective, and remains so, until the desiredconditionsare re-established.

The existence or establishment of the desired condi tions is usuallycaused to manifest itself by the energization of an electromagneticmeans such as a solenoid, and no manipulation whatsoever of the valvehandle or other control is effective to re-open or otherwise reset thevalve until the contemplated energization of the solenoid. occurs. 7

While the invention is primarily directed to the opening and closing, orother setting, of valves, it will be understood that certain phases ofthe invention are of broader scope and may beapplicable to the settingof other mechanisms or devices where it is desired that there be manualcontrol under a pattern of predetermined conditions and an automaticrendering of the manual control ineffective wheneverthere is a deviationfrom such pattern.

While mechanisms of this type are of general utility, they areespecially useful for the operation of .valves that are to functionautomatically under predetermined faulty conditions to interrupt theflow of liquids or, gases, such as fuel, or to initiate flow, as insprinkler systems. This automatic operation functions to disengagemanual operating means in a manner that requires manual reengagementthereof to return the valve to its normal position when the faultyconditions no longer obtain. The automatic operation may be caused to bein response to pressure or temperature changes, the presence or ab.-sence of water vapor or other impurities in a gas, electrical failure,or the happening of other events that may or may not be directlyassociated with the system being controlled.

Prior mechanisms of this nature have often involved relatively expensiveand complicated structures which generally limited their use. Moreovermany of the prior mechanisms required careful and delicate adjustment inorder to insure stability and dependability, thus adding to the cost andcomplication of manufacture. Accordingly it is one object of thisinvention to provide an improved, relatively inexpensive, staunch andreliable free-handle reset valve that can be readily tripped in responseto a departure from a normal or predetermined condition and which may besimply and easily restored to manual control upon the re-establishmentof such-70 Another object of the invention is to provide-a newcondition. 1

2,839,929. Patented June 24, 1958 the handle releasing and valveoperating means may be fabricated by relatively inexpensive proceduressuch as punch press operations and the like and yet provide a highlysensitive and stable mechanism virtually unaffected by frequentactuation and extended use.

Still another object of the invention is to provide a structurecharacterized by its simplicity and positive response to departures frompredetermined or normal conditions.

A further object is to provide a releasable holding means or latchmechanism wherein very small pressures may be used to maintainengagement of the handle and valve to hold the valve in one position andwherein the absence of such slight pressure will effect positive andimmediate disengagement of the handle and permit the:

valve to be instantly moved to another position.

A particular feature of the invention, involving a:

special time-delay mechanism, is applicable not only to.-

their short duration are adequate in magnitude to activate a theelectromagnetic control instrument. For example,'if the latter isarranged to hold the valve in a predetermined. setting so long aselectric power is maintained, and to release or trip it on powerfailure, any momentary power'failure of even one second duration or lessis a source of annoyance. An instance of this would be, for example, theneedless shutting off of gas furnaces with a resultant undesirablecooling before the safety valve can be reset and the furnaces restarted.It is one of the objects of the present invention to obviate thisdisadvantage by means of a time-delay arrangement that bridges over suchmomentary power fluctuations or' failures by delaying the activation ofthe electromagnetic instrument whenever it is conditioned to becomeoperativeto close or open or otherwise operate the valve. 7

The above and other'objects and advantages will become more apparent. inthe following description and accompanying drawings forming part of thisapplication.

In the drawings:

Figure l is a perspective view of a valve constructed in accordance withthe invention, the operating handle being of the wheel type;

Figure 2 is an enlarged cross-sectional view of the line 66 of Figure 8with the operating mechanism in position;

and improved valve of the free-handle type whereinthe engaged position;1

Figure 7 is a cross-sectional view taken along the line' 7.7 of Figure2;

Figure 8 is a partial-cross-sectional view similar to Figure .2 with theoperating mechanism in the engaged vFigure 9 is-a side elevation of thevalve shown in Figure '7taken along the line cover plate removed;

Figures: 10 and l1';are diagrammaticperspective views a 9-9 thereof andwith the' 3' of the operating mechanism in the engaged and disengagedpositions respectively; a

Figure 12 is one embodiment of an electrical circuit for operating thevalve in accordance with the invention;

Figure 13 is a fragmentary view similar to Figure 2, illustrating amodified construction iniwhich the operating handle is of the pivotedlever type; a I

Figures-l4, and 16 are fragmentary views showing the parts in thevarious relative positions they assume during manual control of thevalve; and

Figure 17 is a cross-sectionalview along the line 17-17 of Figure 16. 1

The valve operating mechanism of this invention provides a simple andpositive structure for the attainment of desired safety features and hasthe advantage that only slight pressure is required to maintainoperative engagement of the operating handle with the valve mechanism, arelease of this slight pressure resulting in an instantaneous andpositive disengagement of the handle. This operation involves the use ofa collapsible link assembly between the valve handle and valve disc sothat the major force exerted by the handle to open (or close) the valveagainst the pressure of a valve spring is carried by the links when in afolded or heated position; The links can be maintained in this nestedrelation by only a slight transverse pressure which when releasedpermits the links to collapse and enables the valve to be operatedinstantaneously in response to the valve spring notwithstanding theposition of the operating handle. Furthermore, positive disengagement ofthe handle is effected since the force of the valve spring whichfunctions to close (or open) the valve also causes collapse of thelinksout of nested relation when the transverse pressure is released.

A perspective view ofone embodiment of the invention is shown inFigure 1. In this figure, the valve body is denoted by the numeral 10,and immediately above the body is the mechanism unit 11. The unit 11houses the handle engaging andydisengaging apparatus which I have shownassociated .with a handle of the hand wheel type. The wheel 14 carries athreaded part 13 and cooperates with mechanisms within the cylindricalhousing part 12. While the illustrated embodiment of the invention is ahand wheel operated Y valve it is to be understood that theinvention 'isequally applicable to other types of globe and gate valves, such asthose operated by a lever type handle" (Figure .13.) or wherein thevalve and stem assembly are at right angles or otherwise ar ranged withrespect to the fluid flow.

Referring more specifically to Figures 2 and 7, the

valve body I have chosen to show includes a fluid condiiit 15 havingthreaded end sections 16 and 17 for connection with a system to becontrolled. Joined with the conduit 15 at an angle of about 45 is thevalve housing 18 having a cylindrical opening 19 for receiving certainelements of the valve operating structure. The valve housing 18 isformed integrally with the conduit 15 and comprises part of thesupporting structure for the valve and operating mechanism.

Within the fluid conduit 15 is a valve seat 20 formed in theconventional manner for cooperating with the valve 21. The latter has acylindrical body 22 containing a circular seat 23 of resilient materialretained in position by a circular washer 24 threaded to the cylindricalcenter 4 ing 32 which has a flanged bottom section 33 secured to acorresponding flanged part 34 of the valve body 10 by means of bolts 35.These flanges 33 and 34 are sealed one to the other by means of an Oring 36 retained within a groove 37 in the valve body 10 by a downwardlyextending circular flange 38 formed integrally with the flange 33. Thevalve stem 26 is journaled within a 4 cylindrical bearing 39 having aflange 40 secured to the bottom wall 41 of housing part 32 by bolts 42.An enlarged cylindrical section 43 of bearing 39 cooperates with acorresponding opening in housing 32, and a downwardly extending part ofreduced diameter 44 holds the spring 31 in alignment with the stem 26.This spring 31 is interposed between the flange 40 and valve body 21 andthe lower end of the spring is held in alignment by the head of plug 27.

The valve operating parts 14 and 13 are operatively supported within thehousing 12 extending from the top side of the mechanism unit 11-. Thepart 13 is provided with single or multiple threads 45 which cooperatewith an internally threaded rectangular sleeve or element 46 slidablymounted for longitudinal movement within a flanged guide bearing 47.This bearing is locked in an opening 48 in the upper end of housing 32by means of a sleeve 49 and screws 50. The lower end 51 of the element46 is rigidly secured by rivets 59 to an extension 56 that extendsdownwardly for cooperation with the link assembly. If desired, parts 46and 56 may be 'formed of a single piece. I

The hand wheel and operating assembly are retained in position on thehousing 32 by a flanged plug 52, closing the upper end of sleeve 49 andhaving a central opening 53 for receiving the hand wheel part 13. Withthis arrangement rotation of the hand wheel 14 rotates the part 13relative to the rectangular element 46, moving the latter upwardly ordownwardly depending on the direction of rotation of the wheel. tamedagainst longitudinal movement by lock rings 54 The part 13 is rebearingagainst the plug 52; and the downward movement of the element 46 islimited by a lock ring 55 which cooperates with the upper side of thebearing 47.

Inoperation, when the link assemblywithin the unit 11 operates to couplethe end 51 of element 46 with the upper end. 26"of valve stem 26,rotation of the hand wheel will function to open and close the valve 21in the normal manner. The valve may be fully or partially opened, as maybe desired. Under conditions when the link assembly 'is'collapsed,however, the valve stem 26 is free to move downwardly'under theinfluence of spring 31 to close valve 21, and operation of the handwheel Mwill have no effect whatever on the stem 26.

iThe'link assembly coupling the element 46 with the valve stem26comprises two links 57 and 58. They are shownin the collapsed ordisengaged relationship in Fig u'res '2, 5, 7, 11 and 13. The upper orfirst link 57 is pivotally coupled to the lower end of extension 56 by apivot pin 60. The part 56 is in the form of a channel to accommodate thelink 57 (Figures 6 and 10), and the latter isalso preferably of channelcross-section so as to piece 25 of the valve body 22. The valve stem 26is coupled to the valve body 22 by means of a threaded plug 27 slidablysurrounding the stem 26 and threaded into an opening 28 withinthe piece25. A flange 29 retains the stem in the plug 27 and cooperates withtheplug to open the valve 21 when thestem is lifted; A small spring 30 isinterposed between the flanged end of the valve stem 26 and the bottomof the'cavity 28 and will give under the action of the stem to limit thepressure between the valve body 21 and the seat 20 to that provided bythe main valve spring 31.

.;'Ihe.va1ve and stem assembly is supported the housaccommodate thesecond or lower link 58. The link 58 is pivoted to link 57 by a pin 61and is pivoted at its outer end" by a pm or bolt 62 (Figure 7) to theslotted upper part 26' ofvalve stem 26.

The pivot pin 61 is somewhat longer than the width of the llIlk 57 sothat it can enter a pair of slots 63 in the 'sides of part 56. The link53 is also provided with arecess 64' toreceive the piir when thelinksare in the folded or nested position.

The pivot pin 60 lies and always remainsin the line of valvemovementwhich in this case is coincident with the axis of:the'valve stem26. Actuation of the handle moves the pin60 up. and down along the lineof valve movement but these movements are transmitted to the valveitself With the links in the open position as shown in Figures 2 and 11,it is apparent that vertical displacement of the element 46 by operationof the hand wheel 14 will not function to control the valve. The handleis therefore completely free and ineffective and it cannot beoperatively engaged with the valve until the operating links 57 and 58are moved to and retained in the nested position as shown in Figures '6,8 and 10. 7

To place the liiiks 57 and 58 in the nested position the hand wheel 14is operated to move the element 46 to its downward position. This actionwill cause the links to assume the nested relation, with the ends of thepivot pin 61 engaging the bottom of the slots 63. The depth of theseslots 63 is preferably such that the pin 61 will move to a position justapproaching and closely adjacent to (but not in line with) the centerline of the valve stem 26 and hand wheel element 46. If desired, theslots 63 may be deep enough to allow the pin 61 to come into fullalignment with the center line axis, but in that case provision shouldbe made for some auxiliary force, such as that afforded by a lightspring or the like, to push the linkage out of the dead in-line positionwhen the solenoid is de-energized.

The links are retained in the nested position by a lateral pressureexerted upon them, preferably upon the connecting pivot 61. I have showna triangularly shaped cam or rocker element 65 secured to the wall 66 ofhousing 32 by a rocker pin 67. The pin 67 is carried by cars 68 formedon the rocker 65 and supported by a bracket 69 fastened to the wall 66by screws 70 (Figures and 6). The broad end of the cam plate 65 is bentto provide a sloping surface or cam 71 extending generally in line withthe folded link assembly. This surface 71 cooperates with a roller 72(Figures 5, 6, and 11) carried on one end of the pivot pin 61 so thatwhen the links are in the nested relation and the sloping surface 71 israised as shown in Figures 6 and 10, it will bear transversely againstthe pin 61 to hold the links in the nested positionand against theaction of the main valve spring 31. The sloping surface 71 is made longenough to maintain sliding contact with the roller 72 through its entiretravel from a closed valve position to a fully open valve position. Whenthe plate 65 is rotated in a clockwise direction as viewed in Figures 5and 6, the transverse pressure on roller 72 and pin 61 is releasedwhereupon the links will fly to an open position as shown in Figure 11under the action of valve spring 31.

Operation of the cam plate 65 is controlled by an electromagnetcontained within a housing 73 on the side of the mechanism unit 11 asshown in Figures 5 and 6. The magnet includes a coil or winding 74having a central pole piece 75 terminating at one end within the coiland having its other end threaded for engagement with and support by thehousing 73. A nut 76 may be used to secure this pole'piece in place. Theplunger 77 extends through an opening 78 in the wall 66 and through acorresponding opening in the housing 73 in line with the center polepiece 75 and the central opening of the coil 74. The outer end of thearmature or. plunger 77 is provided with a circular groove 79 forengagement'with a recess. 80 in the rocker 65, and isheld in the upwardposition as shown in Figure 5 by a collar 81 and a spring 82 encirclingthe plunger and held between the collar and the spacer 83 between thehousing 73 and wall 66. Thus when the coil 74 is not energized theplunger 77 moves upwardly, lowering the sloping surface or cam 71 andpermitting. the links 57 and 58 to fly open. When the coil is energizedthe cam 71 is raised as shown in Figure 6 to hold the links in thenested or engaged position.

This" embodiment of the invention includes visual means for indicatingtheposition of the..valve 21 relative to the seat 20. This isaccomplished bymeans of a bracket member 84 (Figure 7 carried by thevalve stem 26. The upwardly extending arm 84' of this bracket liesbehind a window 85 in the cover plate 86 of housing 32 6 as seen inFigures 3 and 7. The window may be provided with markings 87 whichcooperate with means on the bracket arm 84 to indicate the amount thevalve is opened.

In order also to provide a remote indication or signal of opening andclosing of the valve, means are provided in the form of a bell-crankcomprising a shaft 88 (Figures 7 and 9) and a pair of arms 89 and 90 Theshaft 88 is iournaled in the wall 66 of housing 32 and carries on itsinner end the lever arm 89 which cooperates with one end of the pivotpin 62. The outer end of shaft 88 carries the arm 90 which cooperateswith a microswitch 91 within the housing 92 carried on one side ofhousing 32. When the valve stem 26 is in its lowermost position as shownin Figure 7, the pin 62 contacts the recess 89' in arm 89 to move it ina counter-clockwise direction as viewed in Figure 9. This moves the arm90 to actuate the microswitch. When the valve stem 26 is lifted even afew thousandths of an inch the switch is disengaged by arm 90 andreturns to a position indicating that the valve is open. Any suitablesignaling system such as lights,- buzzers and the like, well known inthe art, may be op-' erated by the switch in any desired manner.

As pointed out above, the solenoid 74, 77 functions to control theengagement and disengagement of the valve handle 14 with the valve 21and usually it is desirable to have engagement effected when the magnetis in the energized condition. Experience has indicated thatdisengagement of the handle and closure (or opening) of the valve oftenresults from brief temporary interruptions of the energizing current. Inmost cases it is therefore desirable to interpose a delay system so thattransient effects like these will not operate to actuate the valve.While this may be accomplished in a variety of ways (as for instance theuse of a dash pot mechanically coupled with the solenoid plunger 77), ithas been found that electronic procedures provide the greatest latitudein attaining the desired delay time fora given valve. For this purpose adirect current magnet is employed and means in the form of a condenseris bridged across the coil. In view of the prevalence of alternatingcurrent a typical circuit for attaining this is shown in Figure 12. Analternating current is connected to terminals 93 and 94 and the latteris connected to one terminal 99 of the coil 74. The other terminal 93 isconnected to terminal 98 through the series-connected switch 95,resistor 96 and rectifier 97. When switch is closed, coil 74 will beenergized by the rectified current which is limited by the resistor 96.Delay is eifected by bridging a condenser 100 across coil 74, and theextent of the delay is a direct terminals 93 and 94 can beinterconnected directly with such power source.

. To illustrate the applicability of the features of the in vention to.valves of varying kinds, I have shown in Figures 13-17 how the basiclinkagecan be employed with ahandle of the pivoted lever type;

The links, 101 and 102 are pivoted to each other at 103. The outer endof the upper or first link 101 carries a pin 104 by means of which it isarticulated to the operating handle 105. The outer end of the lower orsecond link 102 is pivoted at 106 to the valve stem to be moved. Exceptfor the mode, of articulation of the linkage to the handle, .it maybeassumed for the purpose of this description that the valve and all itsparts are essentially the same as hereinbefore described.

The pin 104 lies and is maintained in the line of move mentof the valvewhich is, as'before, coincident with the axis of the valve stem 107.When nested in overlying relation the links 101, 102 overlap, as shownin Figures 14-16, and the connecting pivot pin 103 lies in, or: almostin, the line of valve movement. If absolute-alignment, is provided for,a smallauxiliary spring or other force,'as hereinbefore mentioned, isneeded to push the pin 103 out of the deadcenter position when collapseof the linksis to be effected.)

The releasable holding means is the same as that hereinbefore described,comprising a pivoted cam plate 108 having a dimension of adequatemagnitude inthje direction of'valve movement. A cam follower 109 (hereshown as a rounded end on the pin 103) remains in contact with the camplate in all settings of thevalve, so long as the cam is held by theelectromagnetic instrument, such'as a solenoid, in the effectiveposition in which it bears laterally against the follower 109.. Wheneverthe cam plate 108 isshifted aside (e. g., by dp-energization of thesolenoid) the lateral, pressure on the nestedlinks isremoved and theyfly open into the collapsed relation of Figure 13 in which the handle iscompletely ineffective. As in the structure shown in Figures 1-11, themovement of the holding means, viz., the cam plate, from a linkholdingto a link-releasing position, is along a direction transverse to itseffective direction of .pressure against the links so that it withdrawsimmediately from the path of linkage collapse.

The handle 105 is pivoted to thehousing at 110 and is adapted to movebetween the fullline and dotted posi I tions indicated in Figure 13. Inthe construction illustrated a spring 111 (Figure 17) constantly urgesthe handle into the full-line position, but the use of such a spring isnot essential. I

The inner lever arm of the handle 105 is provided with a slot with whichthe pin 104 engages. In'the illustrated embodiment of the invention theinnerarmof the handle is forked, consisting of two spaced arms 112(Figure 17) and each of these arms is provided with the slot referredto, but since the slots are identical and in alignment, and the arms 112move and function as a unit, the,

inner part of the lever is referred to hereinafter as a single arm" 112having a slot 113 formed in it.

In. order that the pin 104 shall always remainin the line of valvemovement its ends are providedwith rolling parts or elements 11.4 thatare caused to ride along fixed guide rails 115, the slot 113 beingcurved, as shown, so as to urge the elements 114 constantly againsttheserails.

When the parts are in the relationship shown in Figure 13 and theconditions required to be met by the particular'installation are faultyor unfulfilled, the handle 105 is ineffective to control movements ofthe valve stem 107, and the latter will remain under the influence of avalve spring (not shown) or other forces to hold it in the positionillustrated. The handle 105 can be moved, but this merely shifts thelinks 101, 102 back and forth between the collapsed and nested positionsand imparts no lifting forceto the valve stem 107. I

Once the required conditions have been established, the cam plate 108will be pivoted from the dotted to the full line position shown inFigure 17, this being accomplished by a solenoid or otherelectromagnetic instrument as hereinbefore described. ,The handle isthen moved to the dotted position shown in'Figu re 13, and during thismanipulation the links 101, 102 fold up into nested overlyingrelationship and the follower 109 snaps into a position behind the humpin the cam plate (Figure 17). The oblique extended margin of the latteris a holding means that now bears lightly against thefollower 1'09 andthusmaintains the links, in nested relation. This condition obtains solong as the solenoid keeps'the holding means effective. in thisrelationship of the parts the handle can'be moved downwardlytFigures 14,15, 16) and this will transmit an eifective force to the valve stem 107to lift in into the desired position.

A release of the holding means to shiftit to dotted position of Figure17 will immediately result and adapted to swing into and out of linkholding postnically; designated valves and has theimportant advantagesof simplicity of structure, complete dependability, and low cost;Moreover the holding mechanism may be readily set and reset without theapplication of large forces and the'only stresses supported by themechanism in the case of the valve shown, for instance, are thoseproduced by the valve operating spring.

While the manually operable handle has been shown in one case in theform of a hand wheel, and in another case in the form of a lever, itwill be understood that the valve may be caused to move by otherwell-known manually operated elements or devices. The term handle asused herein and in the appended claims is intended to include all suchinstrumentalities within its scope.

While only two embodiments of the invention have been illustrated anddescribed it is apparent that many changes and modifications may be madewithout necessarily departing from the true scope and spirit of theinvention as expressed in the appended claims.

. Having thus described my invention what I claim as new and desire tosecure by Letters Patent is:

1. In a mechanism for moving a valve stem or the like along apredetermined line, a handle, a linkage between the handle and stemcomprising a pair of links joined end to end by an intermediate pivot,one of said links having its outer end articulated to the handle and theother link having its outer end pivoted to the stern, said links beingmovable into and out of an overlying relation in which said intermediatepivot is substantially aligned with the line of stem movement, a housingenclosing said linkage, and releasable holding means within said housingand independent of said handle and linkage and adapted to bear laterallyagainst said intermediate pivot to hold the links in overlying relationand therebyr render said handle effective to move said stem.

2. In a mechanism of the character described, the combination ofelements set forth in claim 1, said holding means comprising 'a camhaving an operative surface of substantial dimension parallel to saidline of stem movement.

3. In a mechanism of the character described, the combination ofelements set forth in claim 1, said holding means comprising a cammounted for pivotal movement on an axis parallel to said line of stemmovement and adapted to swing into and out of link'holding position.

14. In a mechanism of the character described, the combination ofelements set forth in claim 1, said holding means comprising a cammounted for pivotal movement on an axis parallel to said line of stemmovement tion, said cam having an operative surface of substantial Vdimension parallel to said line of stem movement.

r5. In a mechanism of the character described, the combination ofelements set forth in claim 1, said hold- 7 ing means comprising a cammounted for movement into and out of link holding position, and anelectromagnet.

having an armature coupled to said cam to control its movement. V

6. In a mechanism for operating a valve stem or the like by movementofthe stem along a predetermined line, a handle, a pair of links pivotedto each other end to end, the first link'having its outer endarticulated to the handle and lying in the line of movement'of the valvestem, the second link having its outer end pivoted I to the valve stem,said links being movable into and'out of an overlying relation in whichtheir 'outer ends are in proximity and the links are substantially inalignment with said line of valve stem movement, and releasable holdingmeans adapted to bear laterally against said links 9 to retain them intheir overlying relation and thereby render the handle effective tooperate the valve stem, said holding means having a substantialdimension parallel to the line of stem movement so that said holdingmeans so long as it is unreleased .remains eifective in all positions ofthe stem.

7. A stem operating mechanism as set forth in claim 6, said handlecomprising a lever mounted for pivotal movement and provided with aslot, said articulation with said first link comprising a pin carried bysaid link and engaging Within said slot.

8. A stem operating mechanism as set forth in claim 7, in combinationWith guide means constraining said pin to remain constantly in the lineof stem movement.

9. A stem operating mechanism as set forth in claim 8, said guide meanscomprising a rail against which said pin bears.

10 10. A stem operating mechanism as set forth in claim 9, said leverslot being contoured to press the pin against said rail in all positionsof the handle.

References Cited in the file of this patent UNITED STATES PATENTS925,673 Zook June 22, 1909 1,644,171 Caldwell Oct. 4, 1927 1,672,049Almquist June 5, 1928 2,014,101 Bryan Sept. 10, 1935 2,218,606 FosterOct. 22, 1940 2,301,876 Hurlburt Nov. 10, 1942 2,456,078 Paille Dec. 14,1948 2,630,832 Lutherer Mar. 10, 1953 FOREIGN PATENTS 191,599 GreatBritain Jan. 18, 1923

